Axial piston pump



m y 4, 1948. w. E. RENIGK 2,440,875

AXIAL PISTON PUMP Filed Sept. 14, 1944 3 Sheets-Sheet l F I c, 3

VENTOR WENDgJ. Rmrqclc @041 K May 4, 1948. w. E. RENICK AXIAL PISTON PUMP 3 Sheis-Sheet 2 Filed Sept. 14, 1944 FIG. 2.

' INVENTOR ELL E.RENICK ATTORNEY May 4, 148.

W.E. RENICK 2,440,875

AXIAL PISTON PUMP Filed Sept. 14,1944

3 Sheets-Sheet 3 INVENTOR ENDE? E.Rnmm

ATTORNEY Patented May 4, 1948 4,440,875 AXIAL PISTON PUMP Wendell E. Renick,

The Denis Ohio,

Columbus, Ohio, on Engineering Company, Columbus, a corporation of Ohio assignor to Application September 14, 1944, Serial No. 554,017 13 Claims. (Cl. 103-162) This invention relates to hydraulic equipment and is particularly directed to improvements in fluid pressure energy translating devices.

One object of this invention is to provide a fluid motor or pump of the axial piston type with improved means for eflecting or controlling the reciprocation of the pistons in their cylinders.

Another object of the invention is to provide an axial piston pump or motor having an eccentrically mounted actuating member for the pistons, which actuating member is provided with a cam surface by means of which the pistons are reciprocated a plurality of times in their cylinder during each cycle of operation of the cylinder barrel.

Another object of the invention is to provide a hydraulic pump or motor having a cylinder barrel joumalled in a casing and ,carrying pistons for reciprocatory movement in the cylinders, the casing having a disk-like member journalled at the end of the cylinder barrel, the member having a ring-like groove in which the ends of the pistons move, the surface of the groove being such that the pistons will be reciprocated when the cylinder barrel is revolved.

A further object of this invention is to provide the disk-like member mentioned in the preceding paragraph with a pair of concentrically arranged inner and outer conical surfaces which are alternately traversed by the pistons during the rotation of the cylinder barrel whereby reciprocatory movement will be imparted to the pistons if the device is employed in the capacity of a pump or a plurality of driving thrusts will be imparted to the cylinder barrel if the device is employed as a motor.

A still further object is to provide the device with hearing means for journalling the disk-like member for rotation about an eccentrically disposed axis relative to the axis of rotation of the :ylinder barrel so that as these members revolve n the operation of the device the pistons will nove first over one conical surface and then )ver the other the different directions of inclinaion causing the pistons to reciprocate in the :ylinder barrel.

An object of the invention also is to provide a iydraulic pump or motor of the axial piston type laving an eccentrically disposed cam-like memer for imparting movement to the pistons and roviding means for supporting the cam-like 1ember so that the axis of rotation may be shifted a vary the eccentricity thereof relative to the xis of rotation of the cylinder barrel whereby he degree of movement of the pistons will be dicated by the line 2 varied between maximum and minimum whereby the capacity of the device will be changed accordingly.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal sectional view taken through a fluid pump or motor formed in accordance with the present invention;

Fig. 2 is a vertical sectional view taken on the plane indicated by the line 2-2 of Fig. 1;

Fig. 3 is a similar view taken on the plane in- 3-3 of Fig. 1;

Fig. 4 is a vertical transverse sectional view taken on the plane indicated between line ii of Fig. 1; and

Fig. 5 is a vertical transverse sectional view taken through a modified form of the invention, having means for varying the capacity of the pump or motor.

Figure 6 is a vertical sectional view taken on the plane indicated by the line 6-6 of Figure 1.

In the form of the invention illustrated in Figs. 1-4, inclusive, the pump or motor comprises, a casing 20 which is of generally cylindrical form. One end of this casing is provided with a head 2| and the other end is provided with a cap 22, the latter being secured to the body 20 of the casing by screws 23 or other suitable fastening elements.

The head 2! is provided with a perforated flange 24 for engagement with a suitable support for the pump or motor, the perforations 25 in the flange being threaded to receive screws or other fas tening elements, not shown, employed in securing the pump to the support. The head 2| is also provided with a central opening 26 through which the operating shaft 2'i of the device extends to the hollow interior 28 of the body 20. Adjacent the outer end of the opening 26 in the head 2|, there is provided anantifriction bearing 29, this member serving to support the shaft 21 for rotation in the pump casing. At the outer side of the bearing 29 the head 2| receives a sealing ring 32 to prevent the escape of hydraulic fluid between the shaft and the head, the sealing ring being clamped in place by a gland 33. Member 33 is secured to the head 2| by machine screws 34.

The inner end of the form a head 35 in which key ways are cut for the reception. of keys 36 which are also positioned shaft 21 is enlarged to in key ways formed in a cylinder barrel 31. This member is supported for rotation in the hollow body 20 by a sleeve bearing 38 which is of a length sufficient to give the cylinder barrel substantial support and prevent wobble or lateral movement thereof during rotation. The bearing 38 engages a shoulder 40 on the cylinder barrel and holds this member so that one end thereof is in firm sliding engagement with a port plate 4| which is secured to the inner end of the head 2|. As shown in Fig. 2, the port plate M is formed with a plurality of circumferentially spaced, elongated, inlet and outlet ports 42 and 43, respectively, two of each ports being provided in this instance. and the ports being alternated, that is, an inlet port being located between the outlet ports. The ports 42 communicate with an inlet passage 44 formed in the head 2| while the ports 43 communicate with an outlet passage 45 formed diametrically opposite the passage 44 in the head 2I. Passages 44 and 45 are threaded, as at 46, at their outer ends for the reception of fluid conductors employed to connect the pump or motor in a fluid system.

As shown in Figs. 1 and 2, the cylinder barrel 31 forms a plurality of cylinders 41 which extend in parallel relation to the axis of rotation of the cylinder barrel. These cylinders 41 are spaced uniformly about the longitudinal axis of cylinder barrel and are fully open at one end to receive pistons 48. The opposite ends of the cylinders 41 alternately communicate through arcuate openings 50 with the inlet and outlet ports 42 and 43 when the cylinder barrel revolves. The inlet and outlet ports 42 and 43 are spaced from each other a distance slightly greater than the length of the openings 53 so that when the cylinder barrel rotates, the imperforate portion of the port plate between adjacent inlet and outlet openings will seal the openings 50 and prevent direct communication between the inlet and outlet ports. Since the openi igs 50 are smaller in width than the cylinders 41, the inner ends of the cylinders will be provided with shoulders which are engaged by spring abutment members 52. These members engage oneend of compression springs, not shown, which are positioned in the interior of the pistons 48. The other ends of the springs engage the inner end walls of chambers formed in the pistons, the expansion of the springs tending to force the pistons out of the cylinders 41. This outward movement of the pistons is controlled through the engagement of the pistons with the surface of a thrust element 53. This element is of generally disk-like form and has a boss 54 projecting from the rear surface. This boss receives the inner race 55 of an antifriction bearing 56, the outer race 51 of which is supported in the cap 22.

It will be noted from an inspection of Figs. 1 and 4 that the center of rotation of the thrust member 53 is eceentrically disposed with relation to the axis of rotation of the shaft 21 and cylinder barrel 31. The reason for this location of the port plate will be apparent from the following description.

As shown in Figs. 1 and 4, one surface of the thrust member 53 is finished to provide a cam surface 58 which includes concentric receding and projecting sections 6!) and GI. The receding surface might readily be termed an interior conical surface, while the projecting section might be considered an exterior conical surface. Due to the eccentric location of the axis of rotation of the thrust member 53, the ends of the pistons 48 will engage the cam surface 58 of the thrust member at points spaced at various distances from the axis of rotation thereof, these points ranging from one adjacent the edge to another adjacent the center of the thrust member and at the opposite side of the axis of rotation thereof.

It will be apparent that as the cylinder barrel revolves the pistons will move over the surface of the thrust member from the edge to a point adjacent the center on the opposite side of the axis of rotation and back to the edge to complete a cycle. In so moving, the pistons cross and recross the groove formed in the cam surface by the receding and projecting sections. The cam surface will thus cause or permit the pistons 48 to reciprocate in the cylinders 41 and when the device is employed as a pump, fluid will be drawn into the cylinders when they are in registration with the inlet ports and expelled therefrom during registration of the cylinders with the outlet ports, each piston performing two complete strokes during one revolution of the cylinder barrel. When the device is employed as a motor, fluid under pressure will be supplied to the inlet of the casing and this fluid will tend to urge the pistons in registration with the inlet ports toward the thrust member causing a reaction to be developed which will impart rotary movement to the cylinder tration with the outlet ports, the projecting sections of the cam surface will cause the pistons to move back into the cylinders and eject the fluid therefrom.

By varying the angularity of the receding and projecting sections of the cam surface, the volume of fluid delivered by speed developed by the device when used as a motor may be changed. It is also possible to change the volume or speed and power by varying the eccentricity of the thrust member relative to the cylinder barrel. In Fig. 5 there has been illustrated diagrammatically one method of .performing this operation. In this form of the invention the thrust member I53 is supported in a bearing I54 which in turn is mounted in an adjustable cage I55. The cage is guided for movement toward and away from the axis of rotation of the barrel, indicated by the letter K in Fig. 5, by guide members I55, these extendin through slots I51 formed in the member I55. The

member I55 is provided with a threaded stud I58 which projects through the housing I69 and receives a knurled adjusting knob I6I at the exterior of the housing. The knob IBI is journalled on the housing so that when it is revolved, the stud I58 will move through the knob NH and in doing so will impart movement to the cage I55. Since the thrust member I53 is carried by the cage, this movement will dispose the axis of rotation of the thrust member either closer to or further away from the axis of rotation of the cylinder barrel.

When these axes coincide the pistons will engage the thrust member near the juncture of the receding and projecting sections of the cam surface and will not move transversely of this cam surface. No longitudinal movement, therefore, will be imparted to the pistons 48. As the thrust member is adjusted to eccentric positions relative to the axis of rotation of the cylinder barrel, the volume will increase in proportion to the change in eccentricity.

While the form of embodiment of the present invention as herein disclosed constitutesa preferred form, it is to be understood that other barrel. When the pistons are in regis-' the pump or the power and forms might be adopted. all coming within the scope of the claims which follow;

I claim: I

A fluid pressure energy translating device comprising, in combination, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately registering with said inlet and outlet ports during rotation of said barrel; piston means mounted for sliding movement in the cylinders in said barrel; and a member disposed for rotation in said casing adjacent the end of said cylinder barrel and about an axis extending parallel to the axis of rotation thereof, said member having an endless groove with surface areas spaced at varying distances from said cylinder barrel, said pistons engaging said surface areas.

2. A fluid pressure energy translating device comprising, in combination, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately registering with said inlet and outlet ports during rotation of said barrel; piston means mounted for sliding movement in the cylinders in said barrel; and a member disposed for rotation in said casing adjacent the end of said cylinder barrel and about an axis disposed in eccentric relation to the axis of rotation of said cylinder barrel, said member having a ring-like groove of V-shaped cross-section, said pistons engaging and traversing the surface of said groove upon rotation of said cylinder barrel.

3. A fluid pressure energftranslating device comprising, in combination, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately registering with said inlet and outlet ports during rotation of said barrel; piston means mounted for sliding movement in the cylinders in said barrel; and a member disposed for rotation in said casing adjacent the end of said cylinder barrel and about an axis parallel and eccentric to the axis of rotation of said cylinder barrel, said member having a ring-like groove with oppositely inclined inner and outer surfaces said pistons engaging and traversing each of said surfaces during the rotation of said cylinder barrel.

4. A fluid pressure energy translating device comprising, in combination, a casing having a port plate with alternately arranged inlet and outlet ports, a cylinder barrel journalledin said casing with an end engaging said port plate, the cylinders therein alternately registering with said inlet and outlet ports; pistons disposed for reciprocation in the cylinders in said barrel; a member disposed in said casing at the other end of said barrel, said member having concentric internal and external conical cam surfaces; and

. means for supporting said member for rotation about an axis disposed in eccentric relation to the axis of rotation of said cylinder barrel, said pistons alternately traversing said conical surfaces during rotation of said cylinder barrel.

5. A fluid pressure energy translating device comprising, in combination, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately registering with said inlet and outlet ports during rotation of said barrel; piston means mounted for sliding movement in the cylinders in said barrel; means for moving said pistons in said cylinder barrel having a surface with a ringlike concavity engaged by said pistons; means supporting said last-named means for rotation rel.

aboutan axis disposed in eccentric relation to the axis of rotation of said cylinder barrel; and means for varying the degree of eccentricity oi. the axis of rotation of said piston moving means.

6. A fluid pressure energy translating device comprising, in combination, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, thecylinders therein alternately registering with said inlet and outlet ports during rotation of said barrel; piston means mounted for sliding movement in the cylinders in said barrel; and means for moving said pistons in said cylinders, said means having a surface with concentric receding and projecting piston engaging sections.

7. In a fluid pressure energy translating device, a casing having inlet and outlet'ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately communicating with said inlet and outlet ports during rotation of said barrel; piston means disposed for sliding movement in said cylinders; and a cam supported for rotation about an axis disposed eccentrically to the axis of rotation of said cylinder barrel, said cam having a ring-like groove in one surface engaged by said pistons, said pistons moving from one side of said groove to the other and back during each revolution'of said cylinder barrel.

8. In a fluid pressure energy translating device, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately communicating with said inlet and outlet ports during rotation of said barrel; piston means disposed for sliding movement in said cylinders; and a aircular plate supported for rotation at one end of said cylinder barrel about an axis disposed eccentrically to the axis of rotation of said cylinder barrel, said plate having a ring-like depression arranged in the surface adjacent said cylinder barrel concentric to the axis of rotation of said plate, said pistons engaging the surface of said depression and moving from one side to the other and back during each revolution of said cylinder barrel.

9. In a fluid pressure energy translating device of the type having a rotary cylinder barrel with cylinders opening to one surface; a valve plate engaging said surface, said valve plate having two pairs of alternately arranged inlet and outlet ports; pistons disposed for reciprocation in the cylinders of said cylinder barrel; and cam means engaging said pistons to effect the reciprocation thereof, said cam means being shaped to impart; two complete reciprocations to each piston during each rotation of said cylinder bar- 10. In a fluid pressure energy translating device of the type having a rotary cylinder barrel with cylinders opening to one surface; a valve plate engaging said surface, said valve plate having two pairs of alternately arranged inlet and outlet ports; pistons disposed for reciprocation in the cylinders of said'cylinder barrel; means for reciprocating said pistons in said cylinder aarrel, said means comprising a plate journalled for rotation about an axis disposed in eccentric relation to the axis of rotation of said cylinder barrel, said plate having a groove in one surface extending concentric to the axis of rotation of said plate, the pistons engaging said grooved surface and moving forward and back across said groove during the rotation of said cylinder barre], the piston in each mum. an. m

7 ward the lowest point in said recess when the cylinder is in communication with an inlet port and toward one side or the other of said recess when the cylinder is incommunication with an outlet port.

11. A fluid pressure energy translating device comprising a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders therein alternately communicating with said inlet and outlet ports during rotation of said barrel; piston means disposed for sliding movement in said cylinders; and means for imparting movement to said pistons, said means having a member supported adjacent one end of the cylinder barrel for rotation about an axis extending parallel to and spaced from the axis of rotation of said cylinder barrel, said member having a piston engaging surface with concentric circular areas inclined toward said cylinder barrel from a circular line between said areas.

12. A fluid pressure energy translating device comprising a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said casing, the cylinders in said barrel being circularly arranged and alternately communicating with said inlet and outlet ports during rotation of said barrel; piston means disposed for sliding movement in said cylinders; and means for imparting movement to said pistons, said means having a member supported adjacent one end of the cylinder barrel for rotation about an axis extending parallel'to and spaced from the axis of rotation of said cylinder barrel, said member having a piston engaging surface with concentric circularareas inclined toward said cylinder barrel from a circular line between said areas, the diameter of said circular line being substantially equal to the diameter of the circle on which said cylinders are arranged.

13. In a fluid pressure energy translating device, a casing having inlet and outlet ports; a cylinder barrel disposed for rotation in said cesing, the cylinders therein alternately communicating with said inlet and outlet ports durin rotation of said barrel; piston means disposed for sliding movement in said cylinders; a cam supported for rotation about an axis disposed eccentrlcally to the der barrel, said cam having a ring-like groove in one surface engaged by said pistons, said pistons moving from one side or said groove to the other and back during each revolution of said cylinder barrel, and means for moving said cam to vary the extent of eccentricity of the axes of the cam and cylinder barrel.

ELL E. RENICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 523,631 Garstang July 24, 1894 1,800,929 Craig Apr. 14, 1931 1,952,994 Laird Mar. 27, 1934 1,996,789 Baker Apr. 9, 1935 2,069,651 Ferris Feb.-2, 1937 2,161,143 Doe et a1. June 6, 1939 FOREIGN PATENTS Number Country Date 293,801 Great Britain Mar. 28, 1939 408,146 Germany Jan. 9, 1925 524,366 g France. May 11, 1921 axis of rotation of said cylin- 

